Just cry a lot and get through it. Just kidding, but it does feel like that sometimes! From what I have seen from people who aren't doing so well - you HAVE to be able to put in the time required for studying. All I hear every class are excuses as to why they don't have time to study. So if you work too much, or have too many kids, your cat catches fire, or have to pick up your best friend from the airport, maybe rethink taking it in the summer, haha.
Also, try to use your lab time wisely. Most people in mine leave an hour or more early and then act all surprised when they fail the mock practical. Don't leave early unless you absolutely must! If you've finished your activities for that day, use that time to study slides, models, etc.
Anyway, sorry, tangent. I have an A so far, and I study every day. YouTube vids have been a great help, as well as taking excellent notes and constantly reviewing those. I also do a lot of practice quizzes to identify areas that need more study. I record my lectures to refer back to. Drawing pictures and diagrams in my notes have helped tremendously for learning some of the more complicated or multi-step mechanisms. Also, make a chart for all the hormones in endocrine. It's a lifesaver.
Good luck!! Feel free to keep asking questions or just get some support! I know how stressful this class is in summer.